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Besides the rapid population growth over the past few decades, water scarcity and soil degradation have intensified the challenges faced by the Iranian agriculture sector to ensure food security over the long term. Despite its paramount importance, the extent to which the land and water resources of Iran can meet the nation’s future food demand is not well understood. Herein, we systematically evaluated the capacity of Iran’s land for sustainable agriculture based on the soil properties, topography, and climate conditions relevant to crop production.Our objectives were to:i) Quantify and map the suitability of Iran’s land resources for croppingii) Examine if further increase in production can be achieved through agriculture expansion or the redistribution of cropping areasWhen evaluated based on the soil and topographic variables only, Iran’s land suitability for crop cultivation can be classified as (million ha): very good 0.7, good 5.1, medium 17.2, poor 24.8, very poor 55.7, and unsuitable 39.7. Inland water bodies, protected areas, urbanized areas, natural forests, and rangelands, collectively occupying 19.3 million ha of Iran’s land, are recognized in this study as excluded areas. When climate variables (precipitation and potential evapotranspiration) were included in the analysis, the distribution of lands among suitability classes were (million ha): very good 0.6, good 3.6, medium 12.8, poor 18.5, very poor 10.2, and unsuitable 97.4. The spatial distribution of these lands is shown in Figure ES-1. Among the considered soil and terrain attributes, low soil organic carbon, steep slope, and high soil sodium content were identified as the most frequent factors limiting the suitability of lands for cropping.Our analysis also revealed that 30%, 5%, and 17% of the current agricultural lands (cultivated and uncultivated) are located in poor, very poor, and unsuitable areas, respectively. Cultivation in very poor or unsuitable lands can be partially avoided as there exist unused lands with at least a medium level of suitability for substitution that can improve the overall sustainability of the agriculture sector in Iran. Our estimation of the proportion of unused lands within each suitability classes shows that almost all available lands with high suitability have been exploited for agriculture, but there exist about 4.2 million ha of medium quality lands, mostly located in western Iran, for future expansion. However, only a small portion of these unused lands can be practically deployed for agriculture because of their low spatial connectivity and limited accessibility. We estimated that cultivating rainfed wheat in 1 million ha of these unused lands could potentially result in the production of 0.8 million ton of wheat per year – adding up to 5% to Iran’s current cereal production level.Whilst the insufficiency of water resources has long been realized as a major impediment to developing a productive agriculture in Iran, our study highlights the additional limitations caused by the paucity of suitable land resources. Our analysis does not consider groundwater availability for agriculture and precipitation is the only component of surface water availability considered in this study. |
